EXHIBIT 10.21
  
                        FOURTH AMENDMENT
                             OF THE
                     GIANT INDUSTRIES, INC.
                     & AFFILIATED COMPANIES
                           401(K) PLAN
  
  
       WHEREAS, Giant Industries, Inc. and certain of its
  affiliates (the "Employer") adopted the Giant Industries, Inc. &
  Affiliated Companies 401(k) Plan (the "Plan") effective July 1,
  1993; and
  
       WHEREAS, the Employer amended and restated the Plan,
  effective July 1, 1993, through an Adoption Agreement dated
  September 10, 1994; and
  
       WHEREAS, the Employer has the authority to amend the Plan.
  
       NOW, THEREFORE, the Employer hereby amends the Plan as
  follows:
  
       Pages 7, and 9 of the existing Plan are hereby removed and
  replaced by the attached replacement pages 7, and 9.
  
       This amendment is effective January 1, 1999, except as
  otherwise stated in the replacement ages of the attachment.
  
                          GIANT INDUSTRIES, INC. &
                          AFFILIATED COMPANIES
  
  12-10-98                By:  /s/ Charles F. Yonker Jr.
  --------                   ----------------------------
  Date                    Name: Charles F. Yonker Jr.
                          Title: Director of Human Resources
  
                          Accepted by:
                          FIDELITY MANAGEMENT TRUST COMPANY,
                          as Trustee
  
  --------                By:----------------------------
  Date                    Name:
                          Title:
  <PAGE>
  <PAGE>
     (3)  ELIGIBILITY REQUIREMENT(S)
  
          A Participant shall be entitled to Employer 
          Contributions for a Plan Year under this Subsection
          (a) if the Participant satisfies the following
          requirement(s) (Check the appropriate box(es) -
          Options (B) and (C) may not be elected together):
  
          (A) [ ] is employed by the Employer on the last day
                  of the Plan Year.
          (B) [ ] earns at least 500 Hours of Service during
                  the Plan Year.
          (C) [ ] earns at least 1,000 Hours of Service during
                  the Plan Year.
          (D) [ ] no requirements.
  
           Note: If option (A), (B) or (C) above is selected
                then Employer Contributions can only be 
                funded by the Employer after Plan Year end.
  
  (b) [X]  DEFERRAL CONTRIBUTIONS
  
      (1)  REGULAR CONTRIBUTIONS 
  
           The Employer shall make a Deferral Contribution in
           accordance with Section 4.01 on behalf of each
           Participant who has an executed salary reduction
           agreement in effect with the Employer for the
           payroll period in question, not to exceed 15*% (no
           more than 15%) of Compensation for that period.
  
           *Effective 01/01/999
  
           (A) A Participant may increase or decrease, on a
               prospective basis, his salary reduction agree-
               ment percentage (check one):
  
                (i) [ ] As of the beginning of each payroll period.
               (ii) [ ] As of the first day of each month.
              (iii) [X] As of the next Entry Date.
               (iv) [ ] (Specify, but be at least once per Plan Year)
                        ____________________________________________
                        ____________________________________________
  
           (B) A participant may revoke, on a prospective basis, a
               salary reduction agreement at any time upon proper
               notice to the Administrator but in such case may not
               file a new salary reduction agreement until (check
               one):
  
                (i) [ ] The first day of the next Plan Year.
               (ii) [X] Any subsequent Plan Entry Date.
              (iii) [ ] (Specify, but be at least once per Plan Year)
                        ____________________________________________
                        ____________________________________________
  
                                               (Replacement Page,
                                                Fourth Amendment)
                                 7<PAGE>
  <PAGE>
  (c) [X] MATCHING CONTRIBUTIONS (only if Section 1.05(b) is checked)
  
      (1) THE EMPLOYER SHALL MAKE A MATCHING CONTRIBUTION ON BEHALF
          OF EACH PARTICIPANT IN AN AMOUNT EQUAL TO THE FOLLOWING
          PERCENTAGE OF A PARTICIPANT'S DEFERRAL CONTRIBUTIONS DURING
          THE PLAN YEAR (check one):
  
          (A) [ ] 50%
          (B) [ ] 100%
          (C) [ ] ___%
          (D) [ ] (Tiered Match) ___% of the first ___% of the
                  Participant's Compensation contributed to the Plan,
  
                  ___% of the next ___% of the Participant's
                  Compensation contributed to the Plan,
  
                  ___% of the next ___% of the Participant's
                  Compensation contributed to the Plan.
  
               Note: The percentages specified above for Matching
                     Contributions may not increase as the percentage
                     of Compensation contributed increases.
  
           (E) [X] The percentage declared for the year, if any, by
                   a Board of Directors' resolution.
  
       (2) [ ] THE EMPLOYER MAY AT PLAN YEAR END MAKE AN ADDITIONAL
               MATCHING CONTRIBUTION EQUAL TO A PERCENTAGE DECLARED
               BY THE EMPLOYER, THROUGH A BOARD OF DIRECTORS'
               RESOLUTION, OF THE DEFERRAL CONTRIBUTIONS MADE BY EACH
               PARTICIPANT DURING THE PLAN YEAR (only if an option is
               checked under Section 1.05(c)(1)).
  
       (3) [X] MATCHING CONTRIBUTION LIMITS (check the appropriate
               box(es)):
  
           (A) [X] Deferral Contributions in excess of 12% of the
                   Participant's Compensation for the period in 
                   question shall not be considered for Matching
                   Contributions.
  
               Note: If the Employer elects a percentage limit in
                     (A) above and requests the Trustee to account
                     separately for matched and unmatched Deferral
                     Contributions, the Matching Contributions 
                     allocated to each Participant must be computed,
                     and the percentage limit applied, based upon
                     each payroll period.
  
           (B) [ ] Matching Contributions for each Participant for
                   each Plan Year shall be limited to $_________.
  
                                            (Replacement Page,
                                             Fourth Amendment)
                               9